search for: start_xmit

...L patch later on. drivers/net/virtio_net.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 3d0ce44..13d0a8b 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -920,6 +920,8 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) int qnum = skb_get_queue_mapping(skb); struct send_queue *sq = &vi->sq[qnum]; int err; + struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum); + bool kick = !skb->xmit_more; /* Free up any pending old buffers before queueing new...

...L patch later on. drivers/net/virtio_net.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 3d0ce44..13d0a8b 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -920,6 +920,8 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) int qnum = skb_get_queue_mapping(skb); struct send_queue *sq = &vi->sq[qnum]; int err; + struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum); + bool kick = !skb->xmit_more; /* Free up any pending old buffers before queueing new...

...ev, vq2txq(sq->vq)); > > __netif_tx_lock(txq, raw_smp_processor_id()); > - free_old_xmit_skbs(sq); > + free_old_xmit_skbs(sq, txq, true); > __netif_tx_unlock(txq); > > virtqueue_napi_complete(napi, sq->vq, 0); > @@ -1505,13 +1509,15 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) > struct send_queue *sq = &vi->sq[qnum]; > int err; > struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum); > - bool kick = !skb->xmit_more; > + bool more = skb->xmit_more; > bool use_napi = sq->napi.wei...

...ev, vq2txq(sq->vq)); > > __netif_tx_lock(txq, raw_smp_processor_id()); > - free_old_xmit_skbs(sq); > + free_old_xmit_skbs(sq, txq, true); > __netif_tx_unlock(txq); > > virtqueue_napi_complete(napi, sq->vq, 0); > @@ -1505,13 +1509,15 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) > struct send_queue *sq = &vi->sq[qnum]; > int err; > struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum); > - bool kick = !skb->xmit_more; > + bool more = skb->xmit_more; > bool use_napi = sq->napi.wei...

...num_sg = skb_to_sgvec(skb, sq->sg + 1, 0, skb->len) + 1; > } > - return virtqueue_add_outbuf(sq->vq, sq->sg, num_sg, skb, GFP_ATOMIC); > + > + return virtqueue_add_outbuf(sq->vq, sq->sg, num_sg, skb, > + GFP_ATOMIC); > } > > static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) > @@ -924,8 +965,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) > struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum); > bool kick = !skb->xmit_more; > > - /* Free up any pending old buffers...

...num_sg = skb_to_sgvec(skb, sq->sg + 1, 0, skb->len) + 1; > } > - return virtqueue_add_outbuf(sq->vq, sq->sg, num_sg, skb, GFP_ATOMIC); > + > + return virtqueue_add_outbuf(sq->vq, sq->sg, num_sg, skb, > + GFP_ATOMIC); > } > > static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) > @@ -924,8 +965,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) > struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum); > bool kick = !skb->xmit_more; > > - /* Free up any pending old buffers...

...f_tx_lock(txq, smp_processor_id()); virtqueue_disable_cb(sq->vq); - sent += free_old_xmit_skbs(sq, budget - sent); + sent += free_old_xmit_skbs(txq, sq, budget - sent); if (sent < budget) { enable_done = virtqueue_enable_cb_delayed(sq->vq); @@ -962,12 +967,13 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum); bool kick = !skb->xmit_more; bool stopped; + unsigned int bytes = skb->len; virtqueue_disable_cb(sq->vq); /* We are going to push one skb. * Try to pop one off to free s...

...f_tx_lock(txq, smp_processor_id()); virtqueue_disable_cb(sq->vq); - sent += free_old_xmit_skbs(sq, budget - sent); + sent += free_old_xmit_skbs(txq, sq, budget - sent); if (sent < budget) { enable_done = virtqueue_enable_cb_delayed(sq->vq); @@ -962,12 +967,13 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum); bool kick = !skb->xmit_more; bool stopped; + unsigned int bytes = skb->len; virtqueue_disable_cb(sq->vq); /* We are going to push one skb. * Try to pop one off to free s...

...rtio_net.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 3d0ce44..13d0a8b 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -920,6 +920,8 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) > int qnum = skb_get_queue_mapping(skb); > struct send_queue *sq = &vi->sq[qnum]; > int err; > + struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum); > + bool kick = !skb->xmit_more; > > /* Free up any pendi...

...; __netif_tx_lock(txq, raw_smp_processor_id()); >>> - free_old_xmit_skbs(sq); >>> + free_old_xmit_skbs(sq, txq, true); >>> __netif_tx_unlock(txq); >>> virtqueue_napi_complete(napi, sq->vq, 0); >>> @@ -1505,13 +1509,15 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) >>> struct send_queue *sq = &vi->sq[qnum]; >>> int err; >>> struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum); >>> - bool kick = !skb->xmit_more; >>> + bool more = skb->xmit_mo...

...; __netif_tx_lock(txq, raw_smp_processor_id()); >>> - free_old_xmit_skbs(sq); >>> + free_old_xmit_skbs(sq, txq, true); >>> __netif_tx_unlock(txq); >>> virtqueue_napi_complete(napi, sq->vq, 0); >>> @@ -1505,13 +1509,15 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) >>> struct send_queue *sq = &vi->sq[qnum]; >>> int err; >>> struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum); >>> - bool kick = !skb->xmit_more; >>> + bool more = skb->xmit_mo...

Now that we have brought the virtio overhead way down with a fast packed ring implementation, we seem to be actually observing TCP drops indicative of bufferbloat. So let's try to enable TSQ. Note: it isn't clear that the default pacing is great for the virt usecase. It's worth trying to play with sk_pacing_shift_update to see what happens. For this reason, and for a more important

Herbert tells me that returning NETDEV_TX_BUSY from hard_start_xmit is seen as a poor thing to do; we should cache the packet and stop the queue. Signed-off-by: Rusty Russell <rusty at rustcorp.com.au> --- drivers/net/virtio_net.c | 57 +++++++++++++++++++++++++++++++---------------- 1 file changed, 38 insertions(+), 19 deletions(-) diff -r a936d320f6d5...

Herbert tells me that returning NETDEV_TX_BUSY from hard_start_xmit is seen as a poor thing to do; we should cache the packet and stop the queue. Signed-off-by: Rusty Russell <rusty at rustcorp.com.au> --- drivers/net/virtio_net.c | 57 +++++++++++++++++++++++++++++++---------------- 1 file changed, 38 insertions(+), 19 deletions(-) diff -r a936d320f6d5...

...sg_set_buf(sq->sg, hdr, hdr_len); num_sg = skb_to_sgvec(skb, sq->sg + 1, 0, skb->len) + 1; } - return virtqueue_add_outbuf(sq->vq, sq->sg, num_sg, skb, GFP_ATOMIC); + + return virtqueue_add_outbuf(sq->vq, sq->sg, num_sg, skb, + GFP_ATOMIC); } static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) @@ -910,10 +950,9 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) struct virtnet_info *vi = netdev_priv(dev); int qnum = skb_get_queue_mapping(skb); struct send_queue *sq = &vi->sq[qnum]; - int err; + int err, q...

...sg_set_buf(sq->sg, hdr, hdr_len); num_sg = skb_to_sgvec(skb, sq->sg + 1, 0, skb->len) + 1; } - return virtqueue_add_outbuf(sq->vq, sq->sg, num_sg, skb, GFP_ATOMIC); + + return virtqueue_add_outbuf(sq->vq, sq->sg, num_sg, skb, + GFP_ATOMIC); } static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) @@ -910,10 +950,9 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) struct virtnet_info *vi = netdev_priv(dev); int qnum = skb_get_queue_mapping(skb); struct send_queue *sq = &vi->sq[qnum]; - int err; + int err, q...

...net->tx_packets (though > without reset to zero, as in vhost_net_tx_packet). > >> 1) sndbuf is not INT_MAX > > You mean the case where the device stalls, later zerocopy notifications > are queued, but these are never cleaned in free_old_xmit_skbs, > because it requires a start_xmit and by now the (only) socket is out of > descriptors? Typo, sorry. I meant out of sndbuf. > A watchdog would help somewhat. With tx-napi, this case cannot occur, > either, as free_old_xmit_skbs no longer depends on a call to start_xmit. > >> 2) tx napi is used for virtio-net &gt...

...net->tx_packets (though > without reset to zero, as in vhost_net_tx_packet). > >> 1) sndbuf is not INT_MAX > > You mean the case where the device stalls, later zerocopy notifications > are queued, but these are never cleaned in free_old_xmit_skbs, > because it requires a start_xmit and by now the (only) socket is out of > descriptors? Typo, sorry. I meant out of sndbuf. > A watchdog would help somewhat. With tx-napi, this case cannot occur, > either, as free_old_xmit_skbs no longer depends on a call to start_xmit. > >> 2) tx napi is used for virtio-net &gt...

...| |ops->sendmsg; (vsock_stream_sendmsg) | | -> alloc_skb; /* it will packet a skb buffer, and include vsock | | * hdr and payload */ | | -> dev_queue_xmit(); /* it will call start_xmit(virtio-net.c) */| |vsock hdr and payload, and then call | +------------------------------------------------------------------+ | | +------------------------------------------------------------------+ |V...

...| |ops->sendmsg; (vsock_stream_sendmsg) | | -> alloc_skb; /* it will packet a skb buffer, and include vsock | | * hdr and payload */ | | -> dev_queue_xmit(); /* it will call start_xmit(virtio-net.c) */| |vsock hdr and payload, and then call | +------------------------------------------------------------------+ | | +------------------------------------------------------------------+ |V...